The present invention relates to a camera which include a display for displaying an image of a subject stored in the camera.
It is known in the prior art to provide an electronic camera which uses an area image sensor. Digital images produced from the image sensor are stored in memory and these images can be shown on a liquid crystal display (LCD) so that the user can determine which image should be stored for use in producing hard copy images. Typically, these images can be stored in a magnetic disk or in a solid state Memory Card.
In U.S. Pat. No. 4,262,301 an electronic camera is disclosed which includes a display device. The camera also includes a digital-to-analog converter which sends signals to the display. Also, the digital-to-analog converter selectively sends these images to a magnetic tape for storage. Images on the magnetic tape can then be produced as a hard copy by a printer which is provided on the camera. A problem with the approach in U.S. Pat. No. 4,262,301 is the difficulty in achieving small product size.
A shortcoming with prior electronic cameras is that the display is of the emissive type. This requires the use of power to generate light. In turn this additional power demand requires a larger battery to power the light generating means. The light generating means often requires additional space. This is the case in the use of the liquid crystal display. The display provides switching elements which control the light. A separate light generating means is required to generate the light.
For simplicity, the invention as described does not include a printing device. It is understood that a printing device may be included without altering the present invention. Such a printing device is disclosed the commonly assigned U.S. patent application Ser. No. 08/951,017 filed Oct. 15, 1997, entitled xe2x80x9cCamera With Microfluidic Printerxe2x80x9d to McIntyre.
Liquid crystal displays (LCD) are, of course, well known in the art and are employed on numerous cameras. Liquid crystal displays use molecules in liquid crystalline phases to change the polarization of light. A user views an image on the display through a pair of cross polarizers which are part of the display. Polarizers can cause a significant amount of light loss degrading a viewed image. In order to overcome this problem, the LCDs use a significant amount of power. Also, it is difficult to get high levels of density variations which can effect the quality of the image on the display.
It is an object of the present invention to provide an electronic camera having a display which can be made small, requires low power levels, and can produce a high quality image.
This object is achieved by an electronic camera, comprising:
a) means for focusing an image of a subject at an image plane;
b) area image sensor means disposed at the image plane for receiving the image subject and producing a digital image having a plurality of pixels that represent the subject;
c) storage means coupled to the area image sensor for storing the digitized image of the subject; and
d) a display for displaying an image corresponding to the stored image, including:
i) field-driven solid phase particles disposed in a matrix that can change reflective density in the display in response to an applied electric field; and
ii) electronic addressing means including electrodes for applying voltages across the field-driven particles at particular locations corresponding to pixels in response to the stored image to produce a displayed image of the subject.
This invention is particularly useful in that solid phase field-driven particle, when used in a display, operate in a reflective mode and use available light to illuminate the image. The use of available light imaging improves viewing the displayed image in areas of high ambient light. Also, it is a feature of the invention that it requires low power and does not require complicated optics found in prior displays.
In bright lighting, emissive displays fail to produce sufficient light output, and the ambient light severely washes out the generated light. The present invention produces superior images in high lighting areas.
This invention has the additional advantage in that non-emissive field-driven particle displays consume less power than traditional emissive displays. This reduction in power requirements reduces battery energy requirements. In turn this permits the use of batteries of lower power and smaller size.
This invention has the additional advantage that non-emissive displays have wider viewing angles than LCDs.
This invention has the additional benefit that non-emissive displays do not require a light generating device. This results in a significant reduction of display volume and thickness.